This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from an application entitled An Insertion Detecting Apparatus earlier filed in the Korean Industrial Property Office on Jun. 16, 1999, and there duly assigned Ser. No. 99-22528 by that Office.
1. Field of the Invention
The present invention relates to an object sensor and, more particularly to an object insertion and separation sensing apparatus and method for detecting whether an object such as a paper cassette of a printer has been inserted into and separated from a predetermined main body.
2. Description of the Related Art
Different mechanisms have been used for detecting whether an object has been inserted or separated from a main body of a device. An example of an object is a paper cassette holding a specific type and size of paper. An example of a device is a printing device such as a printer or copier. There has to be a mechanism that can properly detect when the paper cassette is inserted into the printing device and when the paper cassette is removed from the printing device. Such a mechanism needs to be both economical and durable. The inserted object may sometimes be directly in contact with a switch used to detect the insertion of the object. In such a circumstance, the force of the object such as a paper cassette may damage the switch. The small range of operation of a switch, compared to the distance of movement of an object such as a paper cassette (or tray) increases the likelihood of the switch being damaged. The conventional art discloses an assortment of devices for detecting an object being inserted or removed.
An exemplar of the contemporary art, Shibazaki, et al. (U.S. Pat. No. 4,265,440, Computer-Controlled Paper Feeder, May 5, 1981) discloses a paper cassette that directly contacts a microswitch or reed switch that are positioned adjacent to the exit opening of the cassette. The reed switch can be damaged by the direct force of the paper cassette. Such a solution is not very reliable. Tamehira (U.S. Pat. No. 5,436,418, Cassette Size Detecting Mechanism, Jul. 25, 1995) discloses a copier that can detect different size paper cassettes. When a cassette is inserted, the cassette strikes a detection block which in turn abuts against an actuator portion, which in turn rotates on a hinge portion. The actuator portion has springs that impart force on the switches. Such a solution has many moving parts that may be damaged. The structure of switch operating mechanism is such that a sharp force may impart strong deformity into the structure. Cho et al. (U.S. Pat. No. 5,862,349, Method and Apparatus for Docking and Undocking a Notebook Computer, Jan. 19, 1999), teaches a method and apparatus for detecting if a notebook computer is inserted in the docking station. This method is cost prohibitive in that electrical circuitry has to be installed on both the docking station and the object being inserted like the notebook computer. Daggs (U.S. Pat. No. 5,249,874, Ribbon Cartridge, Oct. 5, 1993) discloses a way of detecting when a ribbon is inserted in a printing device. The switch operating mechanism has an arm with a pivot point. One side is impacted and the other side pivots to impart force on the switch. This method however, allows for only a small range of motion for the object being inserted. Furthermore, the impact force is not dampened in any way to avoid damage to the switch that signifies whether an object has been inserted or not.
To solve the above problems, it is an objective of the present invention to provide an object insertion and separation sensing apparatus having an improved structure so that deformation of a portion directly contacting an object such as a paper cassette inserted and separated can be prevented.
Another objective is to avoid an object directly contacting a switch.
It is a further object have a mechanism that is cost efficient and durable.
It is also an object to have a mechanism for detecting an insertion and separation of an object that is modular because a modular design would allow the mechanism to be manufactured separately, thus allowing a low cost of manufacture.
It is another object to provide more allowance in the distance of the excessive movement of an object when the object enters a main body so that the burden in the manufacture can be lessened.
It is a further object to dampen the amount of force imparted on a switch for detecting the insertion or withdrawal of an object.
Accordingly, to achieve these and other objects, there is provided an object insertion and separation sensing device for detecting the insertion or separation of a predetermined object into or from a main body. The device has a tactile switch installed on a circuit board provided in the main body. An elastic plate is installed and set a predetermined distance from the tactile switch and elastically pressing the tactile switch by an external force. An elastic member is installed to face the tactile switch. The elastic plate is interposed between the elastic member and the tactile switch. Furthermore, the elastic member has one end contacting the elastic plate. A button has one end contacting the other end of the elastic member. The other end of the button is pressed by the object being inserted in the main body, so that the elastic member and the elastic plate are consecutively pressed to operate the tactile switch.